Acute and chronic pain management has been a concern for as long as medicine has been practiced. Several methods of inducing analgesia and anesthesia have been developed. For example, the use of chemical substances is perhaps the most common approach to pain relief which requires suitable substances that are effective, safe to humans, and do not cause complications or abnormal reactions. Despite the great advances that have been made in the field of anesthesiology, and in the field of pain relief in general, there are still some drawbacks to chemical-based approaches.
Radiofrequency (RF) ablation is a technique that has been used in a variety of medical contexts including treatments for cancer and pain relief. During radiofrequency (RF) ablation, current passing through tissue from an active electrode leads to ion agitation, which is converted by means of friction into heat. The process of cellular heating causes coagulation necrosis and consequent cell death. Because ion agitation, and thus tissue heating, is greatest in areas of highest current density (e.g., closest to the active electrode tip), necrosis is limited to a relatively small volume of tissue surrounding the RF electrode. RF ablation, therefore, can be used as an effective treatment of cancer or can be used to selectively ablate unwanted nerve tissue to alleviate and/or reduce pain.
Some painful conditions involve intervertebral disc abnormalities, which have a high incidence in the population. Intervertebral discs are complex structures with dynamic properties resulting from the interaction of a central, gelatinous nucleus pulposus surrounded by a tough, fibrous, semielastic annulus fibrosus. Intervertebral discs may be displaced or damaged due to disease or aging. Disruption of the annulus fibrosus can allow the nucleus pulposus to protrude into the vertebral canal or intervertebral foramen, a condition known as a herniated or slipped disc. A rupture in the annulus fibrosus can allow the escape of nucleus pulposus components. The extruded nucleus pulposus may press on a spinal nerve, which may result in nerve damage, pain, numbness, muscle weakness and paralysis. Furthermore, as a disc dehydrates and hardens due to age or disease, the disc space height will be reduced, leading to instability of the spine, decreased mobility and pain. Moreover, excessive movement of the spinal segments caused by the disc space height reduction could weaken the annulus fibrosus and in certain cases, tear it.
Therefore, there is a need for new ablation devices and methods that effectively ablate a target tissue area. New ablation devices and methods that allow safer and more effective treatments of various intervertebral disc abnormalities such as hernias, tears or bulges in the annulus fibrosus are also needed.